XI. The Eleventh Imam, al-Hasan, called al-'Askari (232/845-260/872)
The son of the tenth Imam , he lived in close confinement in Samarra under the watchful eye of the caliph, especially since it was known that the Shi'ites were awaiting his son, the twelfth Imam, who was to be the promised Mahdi or "guided one", destined to remove injustice from the world. The eleventh Imam married the daughter of the Byzantine emperor, Nargis Khatun, who, following instructions given her in a dream, had sold herself into slavery to become his wife. He is buried in Samarra.